Method and system treating heart malady such as cardiac arrest and heart attack using hypothermia

ABSTRACT

A method for treating cardiac arrest includes defibrillating the patient and/or ventilating the patient and/or administering a cardiac arrest drug such as epinephrine to resuscitate the patient, and then cooling the patient using one or more cooling catheter positioned in the central venous system of the patient.

RELATED APPLICATIONS

This application is a con. U.S. patent application Ser. No. 09/266,452,filed Mar. 11, 1999.

FIELD OF THE INVENTION

The present invention relates to methods and systems for treatingcardiac arrest.

BACKGROUND

It has been discovered that the medical outcome for a patient sufferingfrom severe brain trauma or from ischemia caused by stroke or heartattack is improved if the patient is cooled below normal bodytemperature (38° C.). As understood by the present invention, themedical outcome for many such patients might be significantly improvedif the patients were to be moderately cooled to 32° C.-34° C. relativelyquickly after an ischemic insult for a short period, e.g., 12-72 hours.It is believed that such cooling improves cardiac arrest patientoutcomes by improving the mortality rate, in that many organs canbenefit from the cooling, and by improving the neurological outcome forthose patients that survive.

Systems and methods have been disclosed that propose cooling bloodflowing to the brain through the carotid artery. An example of suchsystems and methods is disclosed in co-pending U.S. patent applicationSer. No. 09/063,984, filed Apr. 21, 1998, owned by the present assigneeand incorporated herein by reference. In the referenced application,various catheters are disclosed which can be advanced into a patient'scarotid artery and through which coolant can be pumped in a closedcircuit, to remove heat from the blood in the carotid artery and therebycool the brain. The referenced devices have the advantage over othermethods of cooling (e.g., wrapping patients in cold blankets) of beingcontrollable, relatively easy to use, and of being capable of rapidlycooling and maintaining blood temperature at a desired set point.

As recognized in co-pending U.S. patent application Ser. No. 09/133,813,filed Aug. 13, 1998, owned by the present assignee and incorporatedherein by reference, the above-mentioned advantages in treating ischemiaby cooling can also be realized by cooling the patient's entire body,i.e., by inducing systemic hypothermia. The advantage of systemichypothermia is that, as recognized by the present assignee, to inducesystemic hypothermia a cooling catheter or other cooling device need notbe advanced into the blood supply of the brain, but rather can be easilyand quickly placed into the relatively large vena cava of the centralvenous system. Moreover, since many patients already are intubated withcentral venous catheters for other clinically approved purposes anyway,providing a central venous catheter that can also cool the bloodrequires no additional surgical procedures for those patients. A coolingcentral venous catheter is disclosed in the present assignee'sco-pending U.S. patent applications Ser. No. 09/253,109, filed Feb. 19,1999 and Ser. No. 09/305,613, filed May 5, 1999, both of which areincorporated herein by reference.

The present invention understands that the above-mentioned benefits ofhypothermia might be particularly suited for treating cardiac arrest.This is because outcomes for cardiac arrest patients currently are verypoor, even when the patients can be resuscitated, since brain damageoccurs as a result of the global ischemia caused by lack of blood flowbefore resuscitation. The severity of such brain damage, as understoodherein, can potentially be alleviated by hypothermia.

SUMMARY OF THE INVENTION

A kit for lowering a patient's temperature includes a first catheterthat has at least one fluid circulation passageway connectable to asource of coolant. In accordance with the present invention, the firstcatheter is configured for placement in a patient's vena cava via agroin entry point. Also, a second catheter has at least one fluidcirculation passageway connectable to a source of coolant. As set forthbelow, the second catheter is configured for placement in a patient'scirculatory system via a neck entry point.

In a preferred embodiment, the kit can include the source of coolant.Preferably, the source of coolant includes at least one thermal electriccooler (TEC) for heating or cooling coolant such that coolant isreturned to the catheter to heat or cool the catheter. The kit can beincorporated in system that includes a ventilation system, and/or adefibrillator system, and/or a component containing a drug selected fromthe group consisting of: epinephrine, buffers, antiarrhythmics, andatropine.

In another aspect, a method for treating cardiac arrest in a patientincludes defibrillating the patient, and lowering the patient'stemperature using at least one catheter placed in the venous system ofthe patient.

In still another aspect, a method for treating cardiac arrest usinghypothermia includes resuscitating the patient and inducing hypothermiain the patient.

In yet another aspect, a system for treating cardiac arrest in a patientincludes at least one cooling catheter that is advanceable into thecentral venous system of the patient. The system further includes one ormore of: a defibrillator, a ventilator, and a cardiac arrest drugdelivery device engageable with the patient.

The details of the present invention, both as to its structure andoperation, can best be understood in reference to the accompanyingdrawings, in which like reference numerals refer to like parts, and inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the cooling system using the first coolingcatheter;

FIG. 2 is a schematic view of the cooling system using the secondcooling catheter;

FIG. 3 is a flow chart of the present invention for treating cardiacarrest in a patient; and

FIG. 4 is a flow chart of the steps for cardiopulmonary resuscitation(CPR).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, a therapeutic system, generallydesignated 10, is shown for treating cardiac arrest in a patient 12. Asshown, the system 10 includes a cooling system 14 that can be awater-bath system such as the system disclosed in the present assignee'sco-pending U.S. patent application Ser. No. 09/220,897 filed Dec. 28,1998 and incorporated herein by reference, or a cooling system includingat least one thermal electric cooler (TEC) 16, as disclosed in thepresent assignee's co-pending U.S. patent application Ser. No.09/260,950, filed Mar. 2, 1999 and incorporated herein by reference. Inany case, the cooling system 14 can be considered a source of coolant,preferably sterile saline, for the catheters of the present invention.

As set forth in these applications, the cooling system 14 can include aheat exchanger, a pump, and, if desired, a controller. Preferably, thepump is a peristaltic pump, but other types of positive displacementpumps, such as but not limited to piston pumps and gear pumps, or evencentrifugal pumps, can be used. A peristaltic pump is preferred in thepresent implementation because it can pump coolant without directlycontacting the coolant, but instead simply by squeezing a tube throughwhich the coolant flows. In this way, the pump is reusable, and only thepresent catheters and portions of the system 10 coming in direct contactwith the coolant need be made disposable to render an advantageouslydisposable and sterile coolant delivery system. The controller controlsthe rate at which coolant is pumped by the pump and, if desired, therate at which heat is added or subtracted from the coolant. Thecontroller can be implemented by a software-executing processor or bydiscrete logic circuits or other electronic circuitry device toestablish a desired patient temperature by appropriately controlling thepump and/or heat exchanger in response to a temperature signal derivedfrom a sensor in the patient 12.

As shown in FIG. 1, a first cooling catheter 18 can communicate with thecooling system 14 via coolant supply and return lines 20, 22. Thecoolant lines 20, 22 can be IV lines or tubes or other suitable fluidconduits, such as metal (steel) tubes. When the coolant lines 20, 22 areplastic tubes, they can be connected to the catheter 18 and the coolingsystem 14 by suitable connecting structure, such as Luer fittings,interference fits, solvent bonding, heat staking, ultrasonic welding,and the like.

The first cooling catheter 18 includes a heat exchange region 24. Theheat exchange region 24 can be established by one or more hollow fibers,as disclosed in the above-referenced U.S. patent application Ser. No.09/133,813. Alternatively, the heat exchange region 24 can include oneor more cooling membranes such as balloons as disclosed in theabove-referenced U.S. patent application Ser. Nos. 09/253,109 and09/305,613. For example, the heat exchange region 24 of the firstcatheter 18 can be established by four axially staggered balloons, eachten millimeters in diameter when inflated with coolant.

In any case, as set forth in the referenced applications, coolant iscirculated in a closed fluid communication loop between the heatexchange region 24 and cooling system 14 to remove heat from the patient12. As set forth in greater detail below, the first catheter 18 isadvanced (preferably through an introducer sheath) into the vena cava ofthe patient 12 through a groin entry point 26 to establish hypothermiain the patient 12. Preferably, the catheter 18 is advanced eitherthrough the saphenous vein or femoral vein in accordance with the methoddescribed below.

In addition to or in lieu of the first catheter 18, a second coolingcatheter 28 (FIG. 2) which is configured for use as a central venouscatheter can be advanced into the central venous system of the patientthrough a neck entry point 29. The second catheter 28 can be embodied bythe catheter disclosed in the above-referenced patent application Ser.Nos. 09/253,109 and 09/305,613. Accordingly, the second catheter 28 cancommunicate with the cooling system 14 via coolant supply and returnlines 30, 32. Also, the second catheter 28 can communicate with one ormore central venous components 34, such as IV infusion devices, drugdelivery syringes for infusing epinephrine, blood withdrawal devices,and so on.

As disclosed in the referenced applications, the second catheter 28includes a heat exchange region 36 that can be established by one ormore membranes such as balloons, although it could be established byhollow fibers in the manner of the catheter 18, but on a smaller scale.The catheter 28 can be advanced into the superior vena cava through thejugular vein or subclavian vein to cool the patient 12 by means ofcoolant circulating in a closed loop between the cooling system 14 andthe balloon 36. As mentioned above, the second catheter 28 can also beused to undertake conventional central venous catheter functions.

Referring back to FIG. 1, in addition to the cooling componentsdiscussed above, the system 10 can include a heart defibrillator system38 that can be engaged with the patient 12 by means of one or moredefibrillator connecting lines 40 with associated engagingpaddles/electrodes 41. Moreover, the system 10 can include a ventilationsystem 42 that ventilates the patient 12 by means of an endotrachealtube 44 or other equivalent device such as a ventilating mask.

The process of the present invention can be appreciated in reference toFIG. 3. Commencing at block 46, basic life support algorithms areundertaken on a patient suffering from cardiac arrest. The basic lifesupport activities can include one or more of the cardiopulmonaryresuscitation (CPR) acts discussed below in reference to FIG. 4.

At block 48, in an attempt to quickly start the patient's heart beatingagain, particularly in the absence of a defibrillator, a precordialthump can be administered to the patient's chest. In addition, or if andwhen the defibrillator system 38 becomes available, at block 50 thedefibrillator is engaged with the patient and the patient isdefibrillated to start the patient's heart beating.

After initial defibrillation, the patient's heart rhythm is assessed atblock 52. At decision diamond 54 it is determined in accordance withcardiac arrest resuscitation standards whether the patient exhibitsventricular fibrillation (VF) or ventricular tachycardia (VT). VF isdefined as a pulseless, chaotic, disorganized rhythm characterized by anundulating irregular pattern that varies in size and shape with aventricular waveform greater than 150 beats per minute. If no VF/VT isdetected, indicating that the patient's heart is beating normally, someor all of the CPR acts shown in FIG. 4 are administered as necessary atblock 56 for, e.g., up to three minutes.

If, on the other hand, it is determined at decision diamond 56 that thepatient exhibits VFVT, the patient is defibrillated up to, e.g., threetimes at block 58. In one preferred embodiment, defibrillation energylevels are 200 J (2 J/kg) for the first shock, 200 J-300 J (24 J/kg) forthe second shock, and 360 J (4 J/kg) for the third and subsequent shocks(weight-based dosages are pediatric recommendations). CPR is thenadministered at block 60 for up to, e.g., one minute.

In accordance with the present invention, after defibrillation and CPR,moderate hypothermia is induced in the patient at block 62 to alleviatethe results of global ischemia arising from cardiac arrest. It is to beunderstood that the step shown at block 62 can be undertaken at otherconvenient times including before defibrillation and CPR or concurrentlytherewith. In any case, the patient's temperature is lowered belownormal body temperature, and as low as 32° C., by advancing one or bothof the catheters 18, 28 into the patient 12 and then circulating coolantthrough the catheter 18, 28.

In one embodiment of the present method, the first catheter 18 isinitially advanced into the vena cava through the groin to cool thepatient while resuscitation personnel require access to the neck forintubation and for establishing rapid IV access. When CPR is complete,the second catheter 28 can be advanced into the vena cava through therelatively less septic neck, and if desired the first catheter 18 can beremoved from the relatively more septic groin area. It is to beunderstood that while this is one preferred sequence of the order ofsteps for inducing hypothermia in a cardiac arrest patient, othersequences can be used. For example, the first catheter 18 can be usedexclusively to the second catheter 28, the second catheter 28 can beused exclusively to the first catheter 18, or both catheters 18, 28 canbe used together simultaneously.

FIG. 4 shows that CPR can include but need not be limited to checkingdefibrillator electrode/paddle engagement on the patient at block 64.Also, CPR can include establishing endotracheal access with the ET tube44 at block 66 and then ventilating the patient using the ventilationsystem 42. If tracheal intubation is not possible, a laryngeal maskairway or Combitube can be used as alternatives.

Moreover, at block 68 intravenous (IV) access can be established usingone of the catheters 18, 28 or another catheter such as a Swan-Ganzcatheter, and then cardiac arrest drugs such as epinephrine can beadministered. If IV access is not attainable, epinephrine can beadministered via the ET tube 44 using at least twice the intravasculardosage of at least 1 mg (0.01 mg/kg) every 3 minutes.

At block 70 other drugs can be considered for administration includingbuffers, antiarrhythmics, and atropine, and the installation of apacemaker can also be undertaken. Any causes that can be corrected (suchas, e.g., blocked airways) are corrected at block 72.

While the particular METHOD AND APPARATUS FOR ESTABLISHING ANDMAINTAINING THERAPEUTIC HYPOTHERMIA as herein shown and described indetail is fully capable of attaining the above-described objects of theinvention, it is to be understood that it is the presently preferredembodiment of the present invention and is thus representative of thesubject matter which is broadly contemplated by the present invention,that the scope of the present invention fully encompasses otherembodiments which may become obvious to those skilled in the art, andthat the scope of the present invention is accordingly to be limited bynothing other than the appended claims, in which reference to an elementin the singular is not intended to mean “one and only one” unlessexplicitly so stated, but rather “one or more”. All structural andfunctional equivalents to the elements of the above-described preferredembodiment that are known or later come to be known to those of ordinaryskill in the art are expressly incorporated herein by reference and areintended to be encompassed by the present claims. Moreover, it is notnecessary for a device or method to address each and every problemsought to be solved by the present invention, for it to be encompassedby the present claims. Furthermore, no element, component, or methodstep in the present disclosure is intended to be dedicated to the publicregardless of whether the element, component, or method step isexplicitly recited in the claims. No claim element herein is to beconstrued under the provisions of 35 U.S.C. ?112, sixth paragraph,unless the element is expressly recited using the phrase “means for”.

What is claimed is:
 1. A method for responding to symptoms of a heartmalady in a patient, comprising the acts of: inducing mild or moderatehypothermia in the patient using at least one catheter placed in thevenous system of the patient by circulating coolant through the catheterwhile the catheter is positioned in the patient's central venous system,such that the coolant does not enter the patient's bloodstream.
 2. Themethod of claim 1, wherein the heart malady is cardiac arrest or heartattack.